1. Field of the Invention
The present invention relates generally to a device for surgically manipulating tissue without damaging the tissue. More particularly, the present invention relates to a tissue manipulating instrument having at least one of sharp extensions, barbs, teeth, serrations, or similar structures of sufficient length to penetrate a tissue surface and having a geometry that resists further incision of tissue whereby torque can be exerted by the distribution of the extensions, barbs, teeth or serrations.
2. Description of Related Art
Several tools have been developed for manipulating tissue by friction, trauma, such as hooking and puncturing, and a combination of friction and trauma which include coacting jaws such as those that are present in forceps and tweezers. The two most common classification for surgical graspers are traumatic and atraumatic.
A traumatic surgical grasper typically has at least one tissue penetrating element on one jaw and often has two coacting or interdentating teeth on the other which function to provide holding power via shear forces that are applied to the hole that is created by penetrating the tissue. For example, U.S. Pat. No. 4,619,260 issued to Magill et al. discloses a tissue-retrieving means for a surgical instrument having a snare loop projecting outwardly for encircling projecting body tissue and means for contracting the loop to sever the encircled tissue. The retrieving means includes tissue engaging means and manipulating means. The tissue engaging means preferably comprises means for impaling the encircled tissue including a barb movable between a contracted position for inserting the barb into the encircled tissue and an expanded position assumed upon the removal of the tissue on the engaging means.
Although effective for certain tissue manipulations, a traumatic surgical grasper is capable of producing undesirable effects. For example, in laproscopic cholecystectomy where prehension of the gall bladder is desired, a traumatic grasper would perforate or tear the gall bladder thereby releasing septic bile into the peritoneal cavity thus causing the patient great danger. Therefore, many instances of tissue manipulation require means for manipulating the tissue without affecting the structural integrity of the tissue.
An atraumatic grasper functions by compressing tissue against jaws that are typically covered with serrated, roughened, or ridged surfaces which are capable of creating friction but are not sharp enough to make incisions into the tissue. One example of such an atraumatic tissue grasper is shown in U.S. Pat. No. 5,275,615 issued to Rose. The Rose patent discloses a forceps type medical instrument with tissue gripping jaws. The jaw arrangement includes a pair of members having opposing wavy and serrated surfaces which open and close against one another to enable tissue to be retained therein by means of friction.
Another atraumatic tissue grasper is shown in U.S. Pat. No. 5,565,004 issued to Christoudias. This patent reference describes a twin forceps approximator having two movable plates joined together at one end and a central plate having the same length which is joined to the two plates at the one end. The two movable plates close against opposite sides of the central plate either simultaneously or sequentially. Teeth are located on the inside surface of the free ends of the plates or jaws in order to engage the tissue between the jaws so that the tissue can be rotated or manipulated.
Many types of tissue forceps exist in the medical instrument art which comprise the basic design of two mobile plates joined at one end. The inside surfaces of these plates often comprise complimentary teeth or ridges which function to hold the tissue between the flexible plates. The size of the plates or jaws, the configuration of the contact surface, and the presence or absence of teeth on the plates or jaws are the characteristics used to categorize and identify the various forceps by name. Most of these tissue forceps are also considered to be atraumatic tissue graspers.
Like traumatic tissue graspers, atraumatic tissue graspers may also produce undesirable effects. More specifically, with respect to the same example used in association with the traumatic tissue grasper, namely laproscopic cholecystectomy, sufficient atraumatic grasper prehension force can create a point load on the gall bladder that can perforate it, or an over pressure to the ligated sac that can induce failure or extravasation.
The present invention overcomes the shortcomings associated with the above described traumatic and atraumatic tissue graspers by distributing the minimally penetrating contact over the tissue micro surface. This provides substantial holding power over the contact surface with less reliance on pressure induced friction. Although the surface of the tissue undergoes multiple incisions by the mechanism of prehension with the present invention, the incisions are of insufficient size to effect the structural integrity of the organ. The present invention also overcomes similar limitations associated with surgical tissue manipulation in general where tissue is simply too slippery to hold or retain easily such as is the case with arthroscopic manipulation of cartilage.